119 citations · 763 across the 29 of their papers we have counts for
21 papers · 1 filter
Paramagnetic electron-nuclear spin entanglement in HoCo2Zn20
Takafumi Kitazawa, Yasuyuki Shimura, Takahiro Onimaru +7
We investigated electron-nuclear spin entanglement in the paramagnetic ground state of the Ho-based cubic compound HoCo2Zn20. From analyses of magnetization and specific heat data,…
Weyl Semimetallic State in the Rashba-Hubbard Model
Katsunori Kubo
We investigate the Hubbard model with the Rashba spin-orbit coupling on a square lattice. The Rashba spin-orbit coupling generates two-dimensional Weyl points in the band dispersio…
Enhanced Spin-Orbit Coupling in a Correlated Metal
Katsunori Kubo
We investigate the correlation effects on spin-orbit coupling (SOC) in a two-orbital Hubbard model on a square lattice by applying the variational Monte Carlo method. We consider a…
Destabilization of ferromagnetism by frustration and realization of a nonmagnetic Mott transition in the quarter-filled two-orbital Hubbard model
Katsunori Kubo
The two-orbital Hubbard model on a square lattice at quarter filling (electron number per site ) is investigated by the variational Monte Carlo method. For the variational wav…
Influence of lattice structure on multipole interactions in non-Kramers doublet systems
Katsunori Kubo, Takashi Hotta
We study the multipole interactions between ions with the non-Kramers doublet ground state under a cubic crystalline electric field. We construct the doublet stat…
Variational Wavefunction for the Periodic Anderson Model with Onsite Correlation Factors
Katsunori Kubo, Hiroaki Onishi
We propose a variational wavefunction containing parameters to tune the probabilities of all the possible onsite configurations for the periodic Anderson model. We call it the full…
Lifshitz Transitions in Magnetic Phases of the Periodic Anderson Model
Katsunori Kubo
We investigate the reconstruction of a Fermi surface, which is called a Lifshitz transition, in magnetically ordered phases of the periodic Anderson model on a square lattice with…
Ferromagnetism and Fermi-surface transition in the periodic Anderson model: Second-order phase transition without symmetry breaking
Katsunori Kubo
We study ferromagnetism in the periodic Anderson model with and without a magnetic field by the Gutzwiller theory. We find three ferromagnetic phases: a weak ferromagnetic phase (F…
Gutzwiller Method for an Extended Periodic Anderson Model with the c-f Coulomb Interaction
Katsunori Kubo
We study an extended periodic Anderson model with the Coulomb interaction Ucf between conduction and f electrons by the Gutzwiller method. The crossovers between the Kondo, interme…
Mass Enhancement in an Intermediate-Valent Regime of Heavy-Fermion Systems
Katsunori Kubo
We study the mechanism of the mass enhancement in an intermediate-valent regime of heavy-fermion materials. We find that the crossovers between the Kondo, intermediate valent, and…
Variational Monte Carlo study of ferromagnetism in the two-orbital Hubbard model on a square lattice
Katsunori Kubo
To understand effects of orbital degeneracy on magnetism, in particular effects of Hund's rule coupling, we study the two-orbital Hubbard model on a square lattice by a variational…
Ferromagnetism and orbital order in the two-orbital Hubbard model
Katsunori Kubo
We investigate spin and orbital states of the two-orbital Hubbard model on a square lattice by using a variational Monte Carlo method at quarter-filling, i.e., the electron number…
Multipole Ordering and Fluctuations in f-Electron Systems
Katsunori Kubo, Takashi Hotta
We investigate effects of multipole moments in f-electron systems both from phenomenological and microscopic viewpoints. First, we discuss significant effects of octupole moment on…
Magnetic Susceptibility of Multiorbital Systems
Katsunori Kubo, Takashi Hotta
Effects of orbital degeneracy on magnetic susceptibility in paramagnetic phases are investigated within a mean-field theory. Under certain crystalline electric fields, the magnetic…
Multipole ordering in f-electron systems
Katsunori Kubo, Takashi Hotta
In order to investigate multipole ordering in f-electron systems from a microscopic viewpoint, we study the so-called Γ_8 models on three kinds of lattices, simple cubic (sc), bcc,…
Analysis of f-p model for octupole ordering in NpO2
Katsunori Kubo, Takashi Hotta
In order to examine the origin of octupole ordering in NpO2, we propose a microscopic model constituted of neptunium 5f and oxygen 2p orbitals. To study multipole ordering, we deri…
Microscopic theory of multipole ordering in NpO2
Katsunori Kubo, Takashi Hotta
In order to examine the mysterious ordered phase of NpO2 from a microscopic viewpoint, we investigate an f-electron model on an fcc lattice constructed based on a j-j coupling sche…
Theory of Coupled Multipole Moments Probed by X-ray Scattering in CeB
Hiroshi N. Kono, Katsunori Kubo, Yoshio Kuramoto
A minimal model for multipole orders in CeB shows that degeneracy of the quadrupole order parameters and strong spin-orbit coupling lead to peculiar temperature and magnetic-fi…
Octupole Ordering Model for the Phase IV of CexLa1-xB6
Katsunori Kubo, Yoshio Kuramoto
An octupole ordering model is studied by the mean field theory, and its relevance to the phase IV of CexLa1-xB6 is discussed. The observed lattice distortion along the [111] direct…
Lattice Distortion and Octupole Ordering Model in CexLa1-xB6
Katsunori Kubo, Yoshio Kuramoto
Possible order parameters of the phase IV in CexLa1-xB6 are discussed with special attention to the lattice distortion recently observed. A Γ_{5u}-type octupole order with finite w…
Interpocket polarization model for magnetic structures in rare-earth hexaborides
Yoshio Kuramoto, Katsunori Kubo
The origin of peculiar magnetic structures in cubic rare-earth (R) hexaborides RB_6 is traced back to their characteristic band structure. The three sphere-like Fermi surfaces indu…